Historic Nor'easter poised to slam Boston and the Northeast U.S.

A potentially historic Nor'easter is brewing for the Northeast U.S., where blizzard watches are up for much of eastern Massachusetts, Rhode Island, and Connecticut. The storm, dubbed "Nemo" by the Weather Channel, is expected to bring heavy snows of 1 - 2 feet, coastal wind gusts over hurricane force, and moderate to major coastal flooding. During the peak of the storm, Friday night into Saturday morning, snowfall rates of 2 - 3" per hour can be expected. These intense bursts of snow may be accompanied by lightning and thunder. The cites of Boston, Hartford, Providence, Portland, and Burlington are all likely to get more than a foot of snow, and two feet of snow will probably fall along a swath from the western suburbs of Boston to Southwest Maine. With the Nor'easter generating these heavy snows expected to bomb out with a central pressure of 972 - 976 mb, the rapid flow of air around this low pressure center will generate ferocious sustained winds near 50 mph at the coast, with wind gusts in excess of hurricane force--74 mph. The combination of heavy snow and high winds will make travel extremely dangerous or impossible, with near-zero visibility in white-out conditions. Total snowfall from the storm is likely to rank in the top ten for Boston since weather observations began at Logan Airport in 1936. According to NWS, here are the top snowstorms since 1936 for Logan Airport:

Figure 1. Predicted wind speeds in knots at 7 am EST Saturday, February 9, 2013, from the 00Z February 7, 2013 run of the European (ECMWF) model. The model is predicting sustained winds of 50 knots (57.5 mph) will affect Cape Cod and Nantucket Island, Massachusetts. Multiply by 1.15 to convert knots to mph.

Serious coastal flooding expected in MassachusettsThe high winds from the storm will drive a damaging storm surge of 2 - 4' along the coast of Eastern Massachusetts Friday night and Saturday morning. Of particular concern is the flooding that will occur during the Saturday morning high tide cycle, as that is the time of the new moon, which will bring the highest tide of the month. The ocean's height in Boston varies naturally by about ten feet between low tide and high tide, so it matters greatly when the storm surge arrives, relative to the tidal cycle. Thus we speak of the "storm tide"--how how the water gets above the high tide mark, due to the combination of the storm surge and the tide. During Hurricane Sandy, on October 29, 2012, a potentially very damaging storm surge of 4.57' hit Boston, but arrived near low tide, so the water level during the peak surge did not rise above the normal high tide mark. As of noon EST on February 7, 2013, the latest storm surge forecast from the GFS model is calling for a storm tide of about 3.4' above high tide (MHHW, Mean Higher High Water) on Saturday morning, which would cause only minor flooding in Boston. This would be the 10th highest water level on record in Boston since tide gauge records began in 1921. According to former NHC storm surge expert Mike Lowry, who now works for TWC, the official top 5 storm tides at the Boston tide gauge, relative to MHHW, are:

More serious flooding is expected in Cape Cod Bay to the southeast of Boston, where the northeast winds from the storm will pile up a higher storm surge. A storm surge of 3 - 4' is predicted from Scituate to Sandwich Harbor Saturday morning. The surge will be accompanied by battering waves 20' feet high, and major flooding and coastal erosion is expected. Major coastal flooding is also expected on the east end of Nantucket Island.

Figure 2. Coastal flooding hazards during the high tide cycle on Saturday morning, February 9, 2013, as predicted at 12 pm EDT Thursday, February 7, 2013, by the NWS Boston.

.SYNOPSIS...1009 MB LOW PRES ACROSS THE MISSISSIPPI COASTALWATERS WILL MOVE E-NE AND INLAND THE FLORIDA PANHANDLE THIS EVENINGWHILE DRAGGING A COLD FRONT CURRENTLY EXTENDING FROM LOW SW TONEAR BROWNSVILLE TEXAS WILL REACH FROM NEAR TAMPA BAY TOBROWNSVILLE FRI MORNING THEN FROM THE FLORIDA KEYS TO BROWNSVILLESAT MORNING BEFORE DISSIPATING SUN. HIGH PRESSURE WILL BUILDWAKE OF THE FRONT...WITH SOUTHERLY RETURN FLOW SETTING ACROSS THENW WATERS ON SAT...THEN INCREASING ACROSS THE ENTIRE GULF SATNIGHT AHEAD OF ANOTHER COLD FRONT THAT WILL MOVE OFF THE TEXASCOAST AROUND SUNRISE SUN. THIS FRONT WILL STALL OVER THE NWWATERS ON SUN...AND DRIFT BACK W TO THE TEXAS COAST ON MON.

Tail of northern low still a little west of me, though looks like a little piece ahead of line heading at us. We're 48, StL is 51 and also ahead of the line, Spfld is 40 and in it now. Winds still not SW yet, SE, S @ 5 gust to 15, 29.84" w/ a 42 dew pt.

BOSTON %u2014Forecasters said Thursday afternoon that there was no change in their prediction that the coming winter storm and blizzard will be "potentially Historic.

The storm will make travel "nearly impossible" on the roads, as it also threatens the coast with flooding and hurricane-force wind gusts. The National Weather Service warned of 5-foot drifts from the storm.

Quoting LargoFl:..ok stay safe up there till this passes you..waterspouts popping up today

I'm not too worried, sadly a dry slot has developed for the Tallahassee area with heavy rain parting north and south. Unfortunately the models often miss these weird mesoscale situations. The last front was more impressive than expected, this one is turning out less eventful then expected for the area, it was much much impressive earlier, looks like the low is quickly ejecting northeast while convergence on the front is sliding southeast ahead of the front in the gulf. That leaves northern Florida in a gap between the two.

Milton Mass................•The Milton Police Department released the following statement on its Facebook page. It has a few reminders as the storm approaches.

Milton residents, as we are all aware, there is the potential for a blizzard in our area Friday into Saturday. Please be mindful of how you remove snow from your property and make sure that house numbers are visible to emergency personnel. Also, please keep hydrants clear. If you have elderly or disabled neighbors, please check in on them. Above all, be safe and stay off the roads if at all possible so the DPW can do their job and clear the streets.

Quoting EricSpittle:That linked forecast is spot on showing me with ~0 ground cover, and matches almost exactly what I am seeing with the models as to addition of snow on top of what the initialization shows from the storm. So I guess the initialized amount doesn't make a huge difference then when looking at storm totals?

If I'm understanding how Mr. Karstens set up his meteogram generator correctly, I think the snow accumulation is 0.0 at T0 (the start time).So in actuality, the rainfall/snowfall accumulation numbers near T0 are shouldn't be taken as the "current rain/snow on the ground."

Quoting EricSpittle:I understand some of what makes snowfall prediction hard, as you said compaction, level of moisture, crystal size, all sorts of different things can make a difference between an inch of precipitation falling as a foot of snow or six inches, I was just curious as to why the baseline seemed so far off and now I think I understand a little bit better.

Unfortunately, a model initializing poorly for current snow depth might cause the model to simulate the future poorly, as it will model the ground as if it were snow and not bare earth/grass/forest/etc. That could change temperature, which could change positioning of storm systems and fronts. Generally-speaking, the more close to observations the initialization is, the better the simulation will be.

Quoting EricSpittle:Do you know roughly how large the grid cells are for these models?

...A POTENTIALLY SIGNIFICANT WINTER STORM TO AFFECT THE AREAFRIDAY INTO EARLY SATURDAY ...

.LOW PRESSURE DEVELOPING NEAR THE COASTAL CAROLINAS LATE TODAY...WILLRAPIDLY INTENSIFY AS IT MOVES TO A POSITION 100 MILES EAST OF ATLANTICCITY LATE FRIDAY AFTERNOON THEN TO NEAR NANTUCKET EARLY SATURDAY.

SNOW THAT FALLS PRIOR TO SUNRISE FRIDAY IN NORTHERN NEW JERSEY ANDEASTERN PENNSYLVANIA WHILE A HAZARD...IS NOT THE PRIMARY EVENT. THEPOTENTIALLY DANGEROUS PORTION OF THIS STORM IS FOR THE FRIDAY EVENINGRUSH HOUR INTO THE WEE HOURS OF SATURDAY MORNING.

Right now here in Raleigh, it's not raining but I think we'll get some heavy rain later today.Rain, mainly after 7pm. Low around 42. North wind 9 to 13 mph. Chance of precipitation is 100%. New precipitation amounts between three quarters and one inch possible.

If the temperatures were colder, we would be facing a foot of snow... *le sigh*

Right, because Almighty scientists never have an ideology, they are always 100% truthful, and they don't have the same human nature as anyone else. I guess they must be different creatures similar to humans, maybe I'm not entirely human either since my career will probably be a scientist.

Most certainly, I'm speaking with sarcasm here, but seriously, if scientists are infallible and never bring an ideology or agenda to the table, I don't think scientists are humans. Furthermore, I'm certainly not inciting any massive conspiracy, and while the scientific method is a great thing, people are still people. They are human like everyone else.

Note, there is no reference to climate change arguments here, but rather a general statement.

Based on figure 2 of Dr. Masters post it looks like the tide will be really bad on the north facing shore of Nantucket Island as the tide will be coming in and the tide will be going out on the south facing shore. This of course is due to the counter-clockwise flow of the storm system and because it will be deepening as it heads north.

OMG... LOVE DORITOS!!! On the more serious note... wish that the global warming... catalytic ice age talk would just stop for a day. More serious for people in NE with this storm. There is DANGER with this. Just me... homeless, are they in shelters?